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Postman

API development platform - visual testing, collections, environments, automated testing

TL;DR

What: API development platform for building, testing, and documenting APIs.

Why: Visual interface, collections, environments, automated testing, team collaboration.

Quick Start

Install: Download from postman.com/downloads

First request:

  1. Click New → Request
  2. Enter URL: https://jsonplaceholder.typicode.com/posts/1
  3. Click Send
  4. View response in bottom panel

Create collection:

  1. Click Collections → Create Collection
  2. Name it “My API”
  3. Add requests to organize

Cheatsheet

FeatureDescription
CollectionsOrganize requests
EnvironmentsVariable sets (dev/prod)
Variables{{variable}} syntax
Pre-request ScriptRun before request
TestsValidate responses
RunnerBatch execute

Gotchas

Environment variables

// Set in environment
// BASE_URL: https://api.example.com
// TOKEN: your-auth-token

// Use in request URL
// {{BASE_URL}}/users

// Use in headers
// Authorization: Bearer {{TOKEN}}

Pre-request script

// Generate timestamp
pm.environment.set("timestamp", Date.now());

// Generate random data
pm.environment.set("randomEmail", `user${Math.random().toString(36).slice(2)}@test.com`);

// Get data from previous request
const token = pm.environment.get("authToken");
pm.request.headers.add({
    key: "Authorization",
    value: `Bearer ${token}`
});

Test scripts

// Check status
pm.test("Status code is 200", function () {
    pm.response.to.have.status(200);
});

// Check response time
pm.test("Response time < 500ms", function () {
    pm.expect(pm.response.responseTime).to.be.below(500);
});

// Check response body
pm.test("Has user id", function () {
    const json = pm.response.json();
    pm.expect(json).to.have.property("id");
    pm.expect(json.id).to.be.a("number");
});

// Save to environment
const json = pm.response.json();
pm.environment.set("userId", json.id);

// Check array
pm.test("Returns array of users", function () {
    const json = pm.response.json();
    pm.expect(json).to.be.an("array");
    pm.expect(json.length).to.be.greaterThan(0);
});

Collection runner

// Run collection with data file (CSV/JSON)
// data.json:
[
    { "email": "[email protected]", "name": "User 1" },
    { "email": "[email protected]", "name": "User 2" }
]

// In request body
{
    "email": "{{email}}",
    "name": "{{name}}"
}

// Access iteration data in tests
pm.test("User created", function () {
    const json = pm.response.json();
    pm.expect(json.email).to.eql(pm.iterationData.get("email"));
});

Newman CLI

# Install
npm install -g newman

# Run collection
newman run collection.json

# With environment
newman run collection.json -e environment.json

# Generate report
newman run collection.json -r html

Next Steps